Interactions of hemoproteins with ligands, particularly the reversible oxygenation process of respiratory pigments (myoglobins and hemoglobins) will be kinetically and thermodynamically analyzed using normal and abnormal pigments and chemically modified compounds in order to correlate the molecular structure of hemoproteins to their physiological functions. Automatic measurements of oxygenation, reaction kinetics, electron paramagnetic resonance and optical absorption spectra by means of on-line computers allow rapid and precise data processing and analysis required for further understanding of the molecular mechanism of these oxygen carriers.